1Heat oven to 350°F (325°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffin cups.
2Make cake mix as directed on box for cupcakes, using water, oil and egg whites. Fold in candy sprinkles until blended. Divide batter evenly among muffin cups.
3Bake 18 to 22 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pans to cooling racks. Cool completely.
4Spoon frosting into decorating bag fitted with 1/2-inch plain tip. On each cupcake, pipe frosting to look like a cloud. Sprinkle with marshmallows. Insert paper umbrella into frosting.